Truck trailers with long beds are equipped with rear axles which are slidably adjustable to move in forward and rearward directions with respect to the truck bed. It is necessary to have axles which are adjustable in this manner because truck trailers carry loads of various sizes which may have horizontal centers of gravity which are closer to one end of the truck bed than the other. During the past decade, regulations have changed, allowing truck trailers of increased length. Such truck trailers almost necessarily must have rear axles which are slidable fore and aft.
In order to properly stop tractor trailers, it is necessary to brake the wheels of the rear axle or axles, as well as the tractor wheels. This is accomplished a pair of hoses, one of which provides pressurized air for normal service braking and the other of which provides pressurized air for emergency braking. In that the rear axles are movable, the air is supplied through flexible conduits which, in a preferable approach, are configured as coiled tubes which expand and contract as the rear axles are moved fore and aft on the trailer bed.
Currently available end fittings for coiled airbrake tubes require additional end fittings for installation, which additional end fittings complicate both installation and maintenance. Moreover, current approaches require NPT or NPTF pipe fittings, which result in additional connections and, therefore, additional points of possible leakage.